Fuel tank equalization

rhakct said:

Peter B (ie Moi), said...
if that's the case, leaving both taps there before the filter open might allow them to equalise at that point as long as that filter is below the fuel levels, saving rigging up yet another connection. Have you tried that? After all, it might be why the PO didn't have a problem..? Then the return fuel line going to just one tank would not matter either, as they would just equalise as you go along.

Don't think this will work either as the fuel lines exit the top of the tanks - at least I've never seen it do it on mine...

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That is irrelevant, as the fuel pick-ups should go down to near the bottom of the tank, and siphon effect should take care of the rest, just as long as the primary filter, where the two shut off valves are situated, is well below the usable fuel level, I would think.

PO on my 34 installed a valve which I can direct the return line to either tank. Generator always goes to starboard tank but engine can be directed either way. I normally direct the return to the tank with less fuel in it which helps keep the listing of the boat to a minimum. If the boat is listing to port, I direct the return flow to starboard.

Did not read every post so excuse if repeating.
You do have a balance line of sorts when both valves are open. With your return line going only to one tank, they should both be open. At least for the time being until you set up your fuel system with two returns.
If your vessel has a "built-in" list, due to generator or battery placement for instance, then a crossover line will make it worse by allowing fuel to flow from the higher to the lower tank.

That is irrelevant, as the fuel pick-ups should go down to near the bottom of the tank, and siphon effect should take care of the rest, just as long as the primary filter, where the two shut off valves are situated, is well below the usable fuel level, I would think.

and therein lies the rub, Mainship installed the primary filter level with the top of the tanks.
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boatpoker said:

ABYC H33 Diesel fuel systems ... (paraphrased) All fuel must return to the tank from which it is drawn.

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My boat has a single engine but two fuel tanks. It draws fuel from both unless I manually close one off. Excess fuel is returned to both tanks unless I manually close one off.

How would the system know which tank the fuel originally came from?

Bill21 said:

Recently bought a 1982 Mainship 34 after years of sailing. Confronted with a distinct list to port and assuming it is caused by an unequal fuel load. Lines from both tanks are open. Starboard tank reads half full, port tank reads empty but suspect sender is inoperative as that is the low side of the boat. Bilge is empty and water tank amidships. Any suggestions will be greatly appreciated. Bill

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I'm going to suggest something that will help you decide if the list is caused by an unequal fuel load as well as determine if your fuel sender is working:

Fill both tanks completely.

Now you know that there is an equal amount of fuel in each tank and you know that both gauges should read "full".

Take it from there.

Excellent suggestion.

I have an 82 MK1 as well, my boat when I purchased it had quite a load of lead bars in a port locker in main cabin. After filling tanks and moving some batteries around removed the lead to balance the boat. My fuel return lines go to both tanks, but no valves to choose which side.